166 



Fertilisers 



[PT. Ill 



Some of the flue dust is now being lixiviated and made 

 to yield muriate or sulphate of potash. 



Raw wool contains a fair amount of potash which is 

 removed during the washing process to which it is sub- 

 jected at the mill. About 500,000 tons of wool are dealt 

 \vith annually in Yorkshire; the potash content varies 

 from very little in wool washed on the farms up to about 

 3 per cent, or more expressed as KgO in unwashed wool. 

 It is impossible to estimate the amount obtainable from 

 this source owing to the paucity of analytical data, but 

 it must be fairly considerable. The extraction of potash 

 used to be carried out in the wool-washing factories in 

 the Roubaix district of France and also in Belgium, and 

 experiments on the subject are now being done in this 

 country^. 



Bracken ash has aroused considerable interest; it 

 contains the following quantities of potash at various 

 stages of its growth^ : 



1 J. p. White, Journ. Textile Institute, 1912, iii. 294-302. A. F. Baker, 

 Journ. Leeds Univ. Textile Assoc, 1915, iv. 69. 

 * Journ. Bd. Agric. 1918, xxv. 1. 



